I've been pondering this question for over 20 years... It's kept me interested and passionate.

I think your friend hit the nail on the head... when we die it will be exactly how it was before you were born. Kinda like that time when you're sleeping but in between dreams. But even less conscious. Think of it this way. Before you were born you were dead for at least 13 billion years or so... and I bet not a single thing that happened during that time was a nuisance... (not sure where that quote came from)

Some people, mostly religious people, think this is a horrible way to end our lives. I think it is beautiful. It makes our time spent here on earth that much more important and precious. Enjoy it.

We do have a purpose. Look at what all life does. It's our blueprint. Life survives, procreates, cares for the herd, spreads its seed, adapts, evolves... continues at all costs. That is our purpose. Let's help our offspring and future generations to do this the best we can. Let's see the big picture. Not just ourselves.

I don't think to have a "purpose" by any sense of the word is exclusive only to a creator...

I've just observed life in all it's shapes and forms and these are things that all life have in common. I've chosen to find purpose in that sense. Mainly to try and contribute the continued survival of humanity by means of technology. If anyone else doesn't care to that's fine by me.

When you talk about purpose, you are open to the question, "According to whom or what?"

Purpose by it's nature implies a direction toward a goal.

If humans have a purpose, and not one they give themselves (to get into Harvard, to write The Great American Novel, to settle down in Montana and raise cattle), then whose purpose are they supposed to be fulfilling?

Once when I was a kid, I asked my father this same question. He answered it like this: Imagine using LEGO blocks to construct a building. Now, suppose the blocks are removed. What happens? The building is gone - poof. That's it.

We are concepts - like a building which is an idea formed by lego blocks; or in our case flesh and bones put together to work in a particular way to generate self-conscious entities. Once the blocks are separated, the idea/ concept of the building is completely destroyed. Similarly, once you die, changes to our body ensures that though matter still exists (our bodies are still there), the idea/ concept of ME is destroyed.

Until science figures out a way to rebuild the matter in our bodies exactly in the same way as before to recapture the concept of 'ME', we will be dead forever.

Will the copy differ from the original in any practical way? If not, can we then consider the copy to be exactly the same as the original?

In Star Trek, when Captain Kirk is 'beamed up', you can assume that information is transmitted (i.e) matter is broken down and reconstructed exactly as before. So, who gets beamed up - a different person or the same?

When we die, we die. We no longer exist, in any way. And that's ok. We're here for a short while, and we do our part, we live our lives, but in the end we're gone. What's left behind is the world we belonged to. What's left behind is our mark on society: the children we raised, the people we affected, or both.

Dying is something truly human. It's not a sense of mortality this concept should lend us, but immortality. Because for all we know, when we die, the world and all it ever was is gone. When we are born, we are given a world to live in, a home that may not be the easiest to live with, but it is our universe. When we die, we will have lived forever in the world that is ours, and as far as for the world that belongs to society, the human race, and whatever else there shall ever be: this world is forever changed by our having been there, as individuals, and our "after life" is how our actions affect the world into the future and how those we loved and knew remember us.

I certainly don't think there is "nonexistence" after death, as though your soul goes in a black box never to be heard from again, although I feel this is a common way to interpret the notion that there is not an afterlife. Frankly, I believe there is something like reincarnation without memory of "past lives," which is to say that it would be a completely discrete and new experience in the universe. My hanging point on this theory is what constitutes a discrete, conscious being, which is obviously a mystery to science or at least very close to being one.

A hazy dream state (without memory) isn't a theory I disregard with the same force as life after death, but it doesn't sit well with me. What experiences this hazy dream state? The reason I warn against the idea of nonexistence is precisely because there is nothing we're aware of, and we're aware of quite a lot, which continues to experience anything other than the mundane after a brain and its body have died. However, it has occurred to me that the body's material must be made part of a living being again in order for anything which was "us" to experience life again, and climbing up the food chain to become a sentient being could take eons.

This is perhaps the most close-to-home reason why I don't want to be buried in a casket. I'm thinking whole-body burial in a burlap sack. Or sky burial. (Can you do that in the "civilized" world?) Cremation wouldn't bother me, either, as long as the ashes went into the soil, not into a jar.

It should be noted that this is entirely superstitious, but any pragmatic decision about what happens to your body naturally is, since, as I'm sure it's been pointed out numerous times in this thread alone, nobody knows, and it's pretty clear we can't know. But if I'm going to make a decision about it, I definitely don't want to be preserved in a state of death. It's creepy, whether you believe you're preserving yourself for reincarnation in this realm or another or you're doing it for posterity for the sake of the living. Creepy, creepy, creepy.